Fases y componentes de un estudio de evaluación

6.1 PREAMBLE

The musculoskeletal conditions have been shown to be more prevalent among persons with diabetes than among control subjects without diabetes.^1-4 The clinical and biochemical factors including poor glycaemic control in DM have been strongly linked with the presence of MSS conditions in DM.^25-27 This study on the prevalence and patterns of musculoskeletal conditions in DM has offered some insight on this topic amongst persons with DM in Lagos in comparisons with non DM control subjects.

6.2 Prevalence of musculoskeletal conditions in Diabetes Mellitus (DM)

Type 2 DM constituted higher percentage of all DM cases studied (type 2 DM-93.2% vs type 1 DM-6.8%). This result is similar to report from most endocrine clinics in Nigeria that documented a percentage of about 90-95% for type 2 DM of all the DM cases.⁸⁷ This present study confirms previous reports of higher prevalence of MSS conditions among subjects with diabetes than the non diabetic controls as it demonstrates that musculoskeletal conditions are 2.5 times more frequent in persons with diabetes than in the control subjects (56% vs 22%, OR-4.5, CI-3-6.5 p-0.0001).^1-4,88-90 This difference is statistically significant such that persons with diabetes have 4.5 times greater risk of developing MSS conditions than non DM subjects. Although, the reported prevalence of MSS conditions among diabetic patients varies widely , this finding is still comparable to prevalence rate of 53.7% documented among Indian diabetic patients²⁴. However it contrasts the prevalence rate of 16.6% reported among Ethiopian diabetics.²⁵.The reason for the wide disparity in the published overall prevalence of MSS conditions among DM patients may be partly explained by i) differences in population demographics and risk

61

factors ii) differing research designs, iii) non uniformity of study population, iv)varying case admixture of rheumatic conditions amongst studies, v) differences in case definitions, vi) varying sample size, vii) varying study subjects, and viii) regional differences in prevalence of diabetes .

6.3 Socio-demography of diabetic subjects with musculoskeletal conditions

In comparison with female control subjects, MSS conditions were more frequently observed than in female diabetic subjects. Similarly, male control subjects had higher frequency of MSS condition than male diabetic subjects, while female subjects generally had higher prevalence of musculoskeletal conditions than male subjects (71.8% vs 28.2%, p< 0.05). This finding is in keeping with previous studies among Africans and non Africans that reported higher prevalence of musculoskeletal conditions among female diabetics^2-3,25. This observation also mirrors background higher prevalence of diabetes among female than male as well as higher prevalence of MSS conditions among female than male in general population.^21,91 On the contrary, a study from India reported equal distribution of MSS conditions between male and female DM patients.¹. While middle aged and elderly persons in general population have been associated with high frequency of MSS conditions due to age related degeneration of articular cartilage and peri-articular structures. This risk was found to increase in the presence of DM,^{54, 25} In this study, the proportion of elderly DM subjects with MSS conditions was significantly higher than elderly controls with MSS conditions while half of the MSS conditions was observed among middle aged DM subjects. This finding differed from a report in USA by Cheng et al⁹⁰, who observed that young diabetic subjects (18-44 years) had higher prevalence of MSS conditions compared with older age group with MSS conditions (22.7% vs 7.2%).

While this study did not find significant difference between the educational level of both

62

DM and control subjects (p=0.63), the majority of subjects in both groups had primary or no education. This finding is in line with the report of low educational attainment among Norwegian DM cases but disagrees with report of higher educational level documented among Indians with DM.^27,1 Diabetic subjects with MSS conditions in this study had significantly less tertiary education than DM cases without MSS conditions(32% vs 48.3% p=0.018). This finding is similar to report by Ashishi et al¹, who documented that DM cases with MSS conditions had lower level of education than DM cases without MSS conditions. Diabetics with higher educational exposure may adhere more strictly to therapeutic lifestyle measures, regular drug therapy and regular clinic visit than diabetic with low or no education, thus translating to fewer complications. This was corroborated by Ogbera et al who documented higher frequency of DM foot (at risk and non at risk foot) among DM subjects with lower education than DM subjects with higher education.⁹²

6.4 Frequency of musculoskeletal conditions in type 1 and type 2 diabetic subjects While the case control study from America³ included equal number of type 1 and type 2 DM subjects and found higher frequency of MSS conditions in type 1 DM subjects than in type 2 DM subjects, some other studies^4,93 including the Ethiopian²⁵ study reported higher frequency of MSS conditions among type 2 DM subjects than type 1 DM subjects.

This study, however, found MSS conditions in 55.6% of all Type 2 DM cases and 61.1%

of all type 1 DM subjects. This result may be due to unequal representations of both types of DM in this study as type 2DM constituted 93.3% of all DM subjects studied.

6.5 Clinical and biochemical characteristics of musculoskeletal conditions in DM Hypertension was significantly more encountered among all DM subjects and DM subjects with MSS conditions compared with control subjects and DM subjects without

63

MSS conditions respectively (p <0.05 in each case). In addition, hypertension was significantly more prevalent among DM subjects with musculoskeletal conditions than in the control subjects with musculoskeletal conditions (p<0.05). In comparison with control subjects with MSS conditions, metabolic syndrome, abdominal obesity, obesity, hyperuricemia, high level of CRP, high level of ESR and presence of co-morbidity were significantly more prevalent among DM subjects with MSS conditions (p <0.05 in each case).The high prevalence of the afore-mentioned biochemical and clinical variables among DM subjects with MSS conditions may reflect background prevalence of these factors among DM subjects in the general populations. In a data from a sample of 7,714 people selected to represent the US population across all ages, metabolic syndrome was prevalent in 59% of patients with osteoarthritis and in 23% of the population without osteoarthritis.⁹⁴ Studies have also found that people with metabolic syndrome develop OA at an earlier age and have more generalised pathology, increased inflammation, and augmented intensive pain in the joints compared to those without^{95, 96}

6.6 Prevalence and types of specific musculoskeletal conditions in diabetes mellitus The prevalence of specific musculoskeletal conditions such as limited joint mobility, symptomatic osteoarthritis, adhesive capsulitis, lumbosacral spondylosis, rotator cuffs tendinitis, gouty arthritis and Dupuytren’s contracture was significantly higher among DM subjects than in the control subjects( p= <0.05 in each case). This finding is in consonance with review article by Smith et al⁷ that showed higher frequency of adhesive capsulitis (DM-11-30% vs control-2-10%), carpal tunnel syndrome (DM:11-16% vs control: 0.13%), Dupuytren’ contracture (DM:20-63% vs control-13%), trigger finger (DM:11% vs control- <1%) and limited joint mobility (DM:8-50% vs control-0-26%) in persons with DM than in the non DM control. A study from Nigeria also documented

64

higher frequency of limited joint mobility among DM subjects than in the non diabetic controls( 19% vs 4%, P<0.01).² The most frequent MSS conditions observed among DM subjects in the present study was limited joint mobility, followed closely by symptomatic osteoarthritis. This finding is in keeping with the report by Ray et al⁹⁷, who documented limited joint mobility as the commonest MSS condition among diabetic subjects but contrary to report of carpal tunnel syndrome as the most frequent MSS manifestation among the Africans²⁵ and adhesive capsulitis among Americans.³ This contrast may be attributed to different scopes of MSS conditions studied by the authors. Most authors assessed limited aspect of MSS system such as shoulder-hand complication or an individual component.^2,25,88-90 Few studies including the present study evaluated the larger components MSS systems, including lower limbs joints, muscles and back.^1,4,.

6.8 Relationship between glycaemic control and MSS conditions in Diabetes Mellitus The current study showed that poor glycemic control was more frequent among diabetic subjects with MSS conditions than DM cases without MSS conditions but no significant statistical difference in poor glycemic controls between the two groups; furthermore, there was no significant difference in mean fasting blood glucose, two hour post-prandial and HBA1C between DM cases with MSS conditions and DM cases without MSS conditions. This trend is in consonant with reports from USA³ and Scotland⁹⁸ that found no significant association between poor glycemic control and MSS conditions among diabetics, however, the reports among Arabs ⁸⁹and Britons⁹³ differed in that they documented significant association between poor glycemic control and presence of MSS complications. Prolonged hyperglycaemia results from poor glycaemic control in diabetes. This causes glycosylation of proteins; microvascular abnormalities; and collagen accumulation in skin and periarticular structures. This results in changes in the connective tissue, and subsequent development articular and peri-articular diseases among diabetics.⁸

65

6.9 Potential predictors of MSS conditions among subjects with Diabetes Mellitus Binary logistic regression analysis showed that history of hypertension, artisans with DM, WBC count, waist circumference, DM of long term duration, and duration of type 2DM were the significant independent predictors of MSS conditions among DM cases. This finding differs somewhat with the result of sex, type of diabetes, and age of DM subjects as independent predictors of MSS conditions among Ethiopians.²² Furthermore, similar to this study, some studies^1,3,26-27 have documented significant association of hypertension, co-morbidity, waist circumference, diabetes of long term duration(at least10 years) and duration of type 2DM with presence of MSS manifestations among DM subjects. Whilst various studies have documented age of DM subjects, type of DM, significant alcohol history, significant smoking history, poor glycemic control, hyperuricemia, obesity, elevated C-reactive proteins, waist-hip ratio, serum uric acid level fasting blood glucose, and HBA1C as independent predictors or associated factors among DM subjects1, 25, 26-27. This present study did not observe any significant association between these variables and MSS conditions among DM cases but noted that some variables such as use of statins, obesity, and hyperuricemia were higher among diabetics with MSS conditions compared with diabetic cases without MSS conditions. The reason for the conflicting report of associated factors could be attributed to varying methodology, sample size and study objectives adopted by different investigators.

66